Electronic transformer



May 8, 1951 C. W. HANSELL ELECTRONIC TRANSFORMER Filed July 11, 1947 I INVENTOR Clawnwlt.

r l t? ATTORNEY Patented May 8, 1951 UNITED STATES ()FFICE ELECTRUNIC TRANSFORMER of Delaware Application July 11, 1947, Serial No. 760,364

13 Claims.

This invention relates broadly to an electronic means by which electrical power of one voltageto-current ratio may be transformed into electrical power of a higher voltage-to-current ratio, and enables by means of a continuous process, a transformation of direct current analogous to that performed in the well known alternating current transformer.

In effect, what the invention accomplishes is to establish a flow or rotation of electron space charge whose velocity represents stored kinetic energy. Then some of this energy is made to transfer itself from one portion of the space charge to another causing one portion of space charge to increase at the same time that the other portion decreases in potential or energy. The portion whose energy has been decreased due to energy transfer to the other portion is then withdrawn from the flow or rotation leaving only electrons with increased energy. As a theoretical limit which can only be approached in practice, when the invention is carried out with a theoretical 100% efliciency, all the energy represented by 100% initial electron input current could be transferred to an electron current only as great, representing thereby a potential increase of about 10 to 1. Any other voltage ratio is theoretically possible.

If it were possible for a stationary observer to view the streams of electron space charge in the device of the invention from any one fixed point, he would see only continuous electron currents flowing over fixed paths in steady state electric and magnetic fields. However, if the observer could imagine himself riding along with the moving space charge, then he would observe that the division of energy in the moving space charge is subject to a transient oscillation from one portion to another. As the oscillation reduces the energy of certain electrons, forming one portion of the space charge, to very low values these electrons are removed from the space charge stream so that they cannot regain the energy they have given up to other electrons in the space charge. This process if continued far enough can, theoretically, result in transfer of all the original energy of the flowing space charge to any remaining fraction and this high energy fraction will represent then a smaller current at higher potential.

A more detailed description of the invention follows in conjunction with a drawing, wherein:

Fig. 1 illustrates one embodiment of the invention, and

Fig. 1a illustrates a cross-section of that por- 2 tion of the tube of Fig. l which includes the ac celerator anode and the X-ray target.

Referring to Fig. 1, I have shown a special form of magnetron-like vacuum tube in which there is provided a permanent magnet l6 producing a magnetic field within the tube which is generally parallel to the axis of a cylindrical electron emitting cathode i2 and a surrounding coaxial cylindrical metallic accelerator anode I4. The cathode has an end plate it at one end to prevent spreading of space charge off the end but there is no end plate, or only a small one H3, at the oth r end. Under this condition, when a positive potential is applied to accelerator anode is with respect to the cathode l2, a rotating electron space charge cloud is set up between the accelerator anode and cathode. As a result of space charge repulsion, or tendency to spread due to similar charges on electrons, a whirling cloud of electrons is projected oil that end of the cathode at which the small end plate 18 is located and away from the large end plate. This whirling cloud rotates in a direction at right angles to the magnetic field and axis of the tube but also moves as a whole parallel to the direction of the magnetic field and the axis of the tube.

A collector electrode 2:] on the axis of the tube projects through the cathode, and this collector electrode is given a positive potential with respect to the cathode by means of lead 22 and direct current power supply 36. It will then collect electrons from the rotating space charge but those electrons which are collected will be only those which have given up almost all the energy with which they were possessed when they moved away from the vicinity of the cathode.

The electrons which are pulled out of the rotating space charge toward the collector electrode 29 are subjected to an angular accelera tion in a direction opposite to their original direction of rotation so that when they arrive at the collector electrode their energy of rotation around the axis is small, and they are then collected with low power loss at the collector. It will thus be seen that those electrons in the whirling cloud which move toward the axis are given an acceleration in a direction to reduce their angular velocity of rotation which they possessed when they were projected away from the cathode, while those electrons in the cloud which are on the outside edge nearest the accelorator anode ltl are given an acceleration in a direction to increase their angular velocity.

In order for the electrons to arrive at the col- 3 lector, it is a prerequisite that they give up energy. It necessarily follows that this energy must go somewhere. This energy is tranferred mostly by encounters with other electrons which are thereby accelerated, and by electromagnetic induction, to that portion of the space charge which has not yet been collected. The device of the invention performs an automatic sorting operation in which electrons which lose energy of rotation move radially toward the collector electrode 20 while those which gain energy of rotation move away from it toward the accelerator anode Hi.

It is not essential that the collector electrode 20 extend the whole length of the accelerator anode since it can collect almost all low energy electrons from the vicinity of the axis at locations on the collector 20 farthest removed from the cathode. These low energy electrons have lost their rotational velocity and can return to the collector along paths such as X, Y and Z which are more or less parallel to the superimposed magnetic field.

lhe result of extracting electrons of low energy continuously from the rotating space charge, as it moves along away from the cathode I2, is that what is left acquires a continually increasin angularly velocity of rotation which, as a limit, may carry electrons out to orbits as large in diameter as the diameter of the accelerator anode l4. By making the magnetic field large, in proportion to the potential between accelerator anode I l and cathode I2, I can make it necessary for any electrons which reach orbits approaching the accelerator electrode diameter to possess energy much greater than that corresponding to the accelerator electrode-to-cathode potential.

By causing these relatively few but very high energy electrons to strike an X-ray target anode 24, which may be in the form of a piece of tungsten projecting inward from the accelerator anode wall, I produce X-rays possessing the properties of rays produced in ordinary X-ray tubes operated at power supply potentials corresponding to the energy of the electrons striking the target. This corresponds to a greater potential than the potential between the collector electrode 20 and cathode i2, and accelerator anode l4 and cathode 2, to which input power is supplied. In the side wall of the accelerator anode l4 adjacent the X-ray target 24 there is provided a light metal X-ray passing window 20 (note Fig. 1a) which enables the X-rays to pass through the accelerator anode and a hole 28 in the magnet 0. The window 20 may be a window of beryllium or other light weight metal when the window must also form part of the evacuated envelope as shown.

In Fig. l, I have shown a permanent magnet for establishing the axial magnetic field and have shown a hole 20 through the magnet to serve as a Window for emerging X-rays. The magnet is shown as having a specially tapered shape of cross-section for the purpose of 'controlling the strength of axial magnetic field in the tube so to make it greater near the target end than near the cathode end of the tube. The resulting taper in magnetic field strength serves to hold the electron orbit diameters more nearly constant as the outer electrons gain energy on the" way from cathode 2 to X-ray target 2 To a large de ree also, the tapered magnetic field causes rotating space charge to be subjected to a force of acceleration backward toward the cathode 12 so that energscorresponding to initial components of electron velocity parallel to the axis, as electrons leave the vicinity of the cathode, is reduced as the electrons move along and this energy is then added to the energy of rotation. An opposing electric field due to a low positive, zero or negative potential applied to a repeller electrode H at that end of the tube which is beyond the ZL-ray target with respect to the cathode can be used in addition to, or in place of, the tapered magnetic field insofar as the axial deceleration of electrons is concerned. As shown, the repeller electrode 3! maybe maintained. at the same or at a negative potential relative to the cathode by means of lead 32 and adjustable resistor 3 5.

It shou d be understood that the position or the X-ray target near the end of the tube, as shown, may not be the optimum one. There is an optimum position for the target somewhere between the cathode end and the other end of the tube and this best position, in each tube design, should be determined by experiment.

An important point to note is that, if the potential between accelerator anode and cathode is say 10,000 volts and electrons are required to strike the target at 100,000 volts then the magnetic field must be strong enough to give substantial magnetron cut-on in the vicinity of the target at potentials up to 100,000 volts. Otherwise the high velocity electrons would be captured by the accelerator electrode anode i l before they con (i reach the target at the required energy levels.

Cne advantage of using the tapered magnetic field as shown in Fig. l is that the diameter of orbit of -ectrons to be accelerated to the higher potentials may be held nearly constant and only a little less than the diameter of the accelerator electrode throughout its length. The arrangement further the advantage that the electron densities may be kept relatively high, which: is a required condition for most efficient energy transfer. In particular, the fact hat the outer whirling space charge moves in an axial direction away from the cathode on the outside and toward the cathode on the inside increases the electron density and allows greater time and distance for energy outward, for any particular length of tube.

It should be understood, of course, that the permanent magnet shown is only one way of producing a magnetic field, and that this may replaced by a long solenoid coil energized by a direct current. This coil should extend over th entire length of the accelerator and should have the turns thereof distributed to provide the desired strength and distribution of magnetic field.

What is claimed is:

1. An electron discharge device system comprising a hollow cathode, a collector anode in the form of a rod passing through the hollow interior of said cathode and extending beyond said cathode into said device, an end plate for said cathode located at the end of said cathode farthest removed from the extending portion of said rod, a tubular metallic accelerator anode surrounding said cathode and rod, means coupled to said rod and accc orator anode for maintaining the same at a potential which is positive relative to said cathode, and means adjacent said accelerator anode for applying a magnetic field having flux lines running parallel to said rod, whereby the electrons emanating from said cathode are given a rotational velocity projected in a stream along the length of said rod.

2. An electron discharge device system 0011'].- prising a hollow cathode, a collector anode in the form of a rod passing through the hollow interior of said cathode and extending beyond said cathode into said device, an end plate for said cathode located at the end of said cathode farthest removed from the extending portion of said rod, a tubular metallic accelerator anode surrounding said cathode and rod and extendin beyond said rod, said rod being tapered down from said cathode toward the end farthest removed from said cathode, means coupled to said rod and accelerator anode for maintaining the same at a D. C. potential which is positive relative to said cathode, and means adjacent said accelerator anode for applying a magnetic field having flux lines running parallel to said rod and which has a greater intensity at the end oi said accelerator anode farthest removed from said cathode than at the other end nearest the cathode, whereby the electrons emanating from said cathode are given both a rotational and an axial velocity.

3. An electron discharge device system comprising a hollow cathode, a collector anode in the form of a rod passing through the hollow interior of said cathode and extending beyond said cathode into said device, an end plate for said cathode located at the end of said cathode farthest removed from the extending portion of said rod, a tubular metallic accelerator anode surrounding said cathode and rod and extending beyond said rod, said rod being tapered down from said cathode toward the end farthest removed from said cathode, means coupled to said rod and accelerator anode for maintaining the same at a D. C. potential which is positive relative to said cathode, means adjacent said accelerator anode for applying a magnetic field having iiux lines running parallel to said rod and which has a greater intensity at the end of said accelerator anode farthest removed from said cathode than at the other end nearest the cathode, whereby the electrons emanating from said cathode are given both a rotational and an axial velocity, and a target within said tubular accelerator anode at a location between the tapered down end of said rod and the location of greatest magnetic field intensity.

4. An electron discharge device system cone prising a hollow cathode, a collector anode in the form of a rodpassing through the hollow interior of said cathode and extending beyond said cathode into said device, an end plate for said cathode located at the end of said cathode farth st removed from the extending portion of said. rod, a tubular metallic accelerator anode surrounding said cathode and rod and extending beyond said rod, said rod being tapered down from said cathode toward the end farthest removed from said cathode, means coupled to said rod and accelerator anode for maintaining the same at a D. C. potential which is positive relative to said cathode, means adjacent said accelerator anode for applying a magnetic field having flux lines running parallel to said rod and which has a greater intensity at the end of said accel rator anode farthest removed from said cathode than at the other end nearest the cathode, whereby the electrons emanating from said cathode are given both a rotational and an axial velocity, and an X-ray target within said tubular accelerator 6 anode at location between the tapered down end of said rod and the location of greatest magnetic field intensity, said metallic accelerator anode having a low mass window adjacent said target.

5. An electron discharge device system comprising a hollow cylindrical cathode, an electron r peller electrode at one end of said device facing the interior of said device, a rod extending from said cathode along the axis thereof to a point therebeyond in the interior or" said device and being tapered down toward the end farthest removed from said cathode, a metallic accelerator anode surrounding said cathode and rod and extending beyond the tapered down end of said rod, means coupled to said rod and accelerator anode and said repeller electrode for maintaining said rod and accelerator anode at a positive potential and said rcpeller electrode at a negative poten tial relative to said cathode, and adjacent said accelerator anode for applying an axial mag netic field to said device.

6. An electron discharge device comprising a hollow cathode, a collector anode in the form of a rod passing through the hollow interior of said cathode and extending beyond said cathode into said device, an end plate for said cathode located at the end of said cathode farthest removed from the extending portion of said rod, a tubular metallic accelerator anode surrounding said cathode and rod, and magnetic means surrounding said metallic accelerator anode for applying a magnetic field having flux lines running parallel to said rod, whereby the electrons emanating from said cathode are given a rotational velocity and projected in a stream along the length of said rod.

'7. An electron discharge device comprising a hollow cathode, a collector anode in the form of a rod passing through the hollow interior of said cathode and extending beyond cathode into said device, an end plate for said cathode located at the end of said cathode farthest removed from the extending portion or" said rod, a tubular metallic accelerator anode surrounding said cathode and rod and extending beyond said rod, said rod being tapered down from said ca hode toward the end farthest removed from said cathode, and magnetic means surrounding said metallic accelerator anode for applying a magnetic field having fiux lines running parallel to said rod and which has a greater intensity at the end of said accelerator anode farthest removed from said cathode than at the other end nearest the oathode, whereby the electrons emanating from said cathode are given both a rotational and an axial velocity.

8. An electron discharge device comprising a hollow cathode, a collector anode in the form of a rod passing through the hollow interior of said cathode and extending beyond said cathode into said device, an end plate for said cathode located at the end of said cathode farthest removed from the extending portion of said rod, a tubular metallic accelerator anode surrounding said cathode and rod and extending beyond said rod, said rod being tapered. down from said cathode toward the end farthest removed from said cathode, magnetic means surounding said metallic accelerator anode for applying a magnetic field having flux lines running parallel to said rod and which has a greater intensity at the end or" said accelerator anode farthest removed from said cathode than at the other end nearest the cath ode, whereby the electrons emanating from said cathode are given both a rotational and an axial velocity, and a target within said tubular accelerator anode at a location between the tapered down end of said rod and the location of greatest magnetic field intensity.

9. An electron discharge device comprising a hollow cathode, a collector anode in the form of a rod passing through the hollow interior of said cathode and extending beyond said cathode into said device, an end plate for said cathode located at the end of said cathode farthest removed from the extending portion of said rod, a tubular metallic accelerator anode surrounding said cathode and rod and extending beyond said rod, said rod being tapered down from said cathode toward the end farthest removed from said cathode, magnetic means surrounding said metallic accelerator anode for applying a magnetic field having flux lines running parallel to said rod and which has a greater intensity at the end of said accelerator anode farthest removed from said cathode than at the other end nearest the cathode, whereby the electrons emanating from said cathode are given both a rotational and an axial velocity, and an X-ray target within said tubular accelerator anode at a location between the tapered down end of said rod and the location of greatest magnetic field intensity, said metallic accelerator anode having a low mass window adjacent said target.

10. An electron discharge device comprising a hollow cylindrical cathode, an electron repeller electrode at one end of said device facing the interior of said device, a rod extending from said cathode along the axis thereof to a point therebeyond in the interior of said device and being tapered down toward the end farthest removed from said cathode, a metallic accelerator anode surrounding said cathode and rod and extending beyond the tapered down end of said rod, means for maintaining said rod and accelerator anode at a positive potential and said repeller electrode at a negative potential relative to said cathode, and magnetic means surrounding said metallic accelerator anode for applying an axial magnetic field to said device.

11. In an electron discharge device system, an electron discharge device, means for setting up a rotating electronic space charge in said device,

means for expanding said space charge both inwardly and outwardly with respect to the axis of rotation to thereby transfer energy from the portion which expands inwardly to the portion which expands outwardly, as a result of which the portion which expands outwardly gains energy from the portion which expands inwardly, means for removing the portion which loses energy comprising a metallic rod extending longitudinally along the axis of the discharge device in the interior thereof, and means fOr utilizing solely the portion which gains energy comprising a target adapted to be impinged upon by the outwardly expanding portion.

12. An electron discharge device comprising a hollow cathode, a collector anode in the form of a rod passing through the hollow interior of said cathode and extending beyond said cathode into said device, a tubular metallic accelerator anode surrounding said cathode and rod, and magnetic means adjacent said metallic accelerator anode for applying a magnetic field having flux lines running parallel to said rod.

13. An electron discharge device comprising a hollow cathode, a collector anode in the form of a rod passing through the hollow interior of said cathode and extending beyond said cathode into said device, a tubular metallic accelerating anode surrounding said cathode and rod and extending beyond said rod, said rod being tapered down from said cathode toward the end farthest removed from said cathode, and a permanent magnet adjacent said metallic accelerator anode for applying a magnetic field having flux lines running parallel to said rod.

CLARENCE VI. HANSELL.

REFERENCES CITED one following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,071,748 Hund Feb. 23, 1937 2,108,900 Peterson Feb. 22, 1938 2,297,305 Kerst Sept. 29, 1942 2,352,657 Potts July 4, 1944 

